Fos a proto-oncogenic transcription factor of the bZIP family. Dimerizes with proteins of the JUN family, thereby forming the transcription factor complex AP-1. FOS proteins function as regulators of cell proliferation, differentiation, and transformation. In some cases, expression of FOS has also been associated with apoptotic cell death. Expression increases upon a variety of stimuli, including growth factors, cytokines, neurotransmitters, polypeptide hormones, stress and cell injury.
